Effect of washing and disinfecting containers on milk quality in Mali

1. Effect of washing and disinfecting containers on milk quality in Mali Bassirou Bonfoh1, Cornélia Roth2, Ami N. Traoré3, Adama Fané3, Cheick F. Simbé3, Idriss O. Alfaroukh1, Jacques Nicolet4, Jakob Zinsstag5, Zakaria Farah2 1Institute of Sahel, Bamako, Mali. 2 Swiss Federal Institute of Technology, Zurich, Switzerland. 3Central Veterinary Laboratory, Bamako, Mali. 4Institute for Veterinary Bacteriology, University of Berne. 5Swiss Tropical Institute, Basle, Switzerland. www.laitsain.com 1. INTRODUCTION 3. RESULTS & DISCUSSION 3.1 Effect on container’s and water microbiological quality Milk and milk products sold in Bamako are highly contaminated with more than 107 colony forming units per ml (CFU.ml-1). This reflects the local production conditions and poses a practical challenge as milk is produced and marketed without cold chain, clean water, limited access to energy, and long time transportation (poor road network). The risk factors assessment also showed the contribution of milk containers to the poor milk microbiological quality. The TC was significantly reduced by the intervention in the Plastic calabash, the farmers and the vendors can (Fig. 2). The different actors complied (S2) with hygienic procedures at the level of the farmers and the vendors containers, where TC remained significantly lower compare to S0. The farmers container’s washing and disinfection reduced the log TC by 1 (S2) to 3.5 (S1). The study aimed to demonstrate the efficacy of soap washing and sodium hypochlorite disinfection on milk quality. 2. MATERIALS & METHODS 2.1 Sampling and microbiological analysis Water (n=9), container’s samples (rinsed water, n=18) and milk samples (from the udder to the selling point) were collected at three sequences: control (S0), intervention (S1) and Compliance (S2). Total counts (TC) was performed on milk at each critical control point (CCP): milk from individual cow (CIM, n=27); Pooled milk from farmer (PMF, n=9); Pooled milk from vendor at farm (PMV-F, n=9) and PMV at the market (PMV-M, n=9). 1) Calabash removed after control Fig.2: Effect of hygiene package on Log10 of TC ml-1 of different sources of contamination: Prior to S0, S1 and S2. Levels of significance of the Z-test for differences between S1 and S0, S2 and S0, respectively. * = p < 0.05; ** = p < 0.01; *** = p < 0.001; n.d. = not done (too small sample size) 3.2 Effect on milk microbiological quality The interventions S1 significantly reduced TC compared to S0 at the levels of the farmer’s and the vendor’s (market) pool (Fig. 3). The compliance with the hygienic package S2 reduced TC at all CCP (at the level of the vendors container on the farm, the algorithm did not converge).On the market (PMV-M), the milk TC decrease by more than 90% with the intervention (S2) and by more than 80% with the compliance (S2) compared to the control sequence (S0). However, the final bacteriological quality of the milk (< 106 CFU/ ml) found at the selling point could allow it’s pasteurisation. Fig. 1: Milk chain (from the cow’s udder to the first selling point) 2.2 Cost evaluation The quality improvement cost was evaluated using farmer’s basic input plus the hygiene package input. The opportunity cost of labour was considered as nil. • α = Intervention cost (Fcfa) • FI = Farmer investment (Fcfa) • FR = Farmer revolving funds (Fcfa) • Dx = life period of the equipment or revolving point (day) • VI = Vendor's investment (Fcfa) • VR = Vendor's revolving funds (Fcfa) • c = control (basic investment before intervention) • m = hygiene package (intervention) Fig. 3: Evolution of milk contamination (log10 total counts) between CCP and sequences S0, S1 and S2.. 3.2 Cost of milk quality improvement The total cost of the hygiene package was evaluated at 85 150 Fcfa, where the milk aluminium can represents 89.3%. Both farmer and milk vendor spent an average of 33 Fcfa/ day (control S0). The hygiene package cost 72 Fcfa/ day, giving the milk quality improvement cost of 39 Fcfa/day. 2.3 Stratified Poisson regression • Population: milk samples from CCP • Variable: log10TC in the generalized estimating equations (GEE). • Factors: sources of contamination (containers, water, udder) and temperature • Random effect: cow, repeated statement with an exchangeable correlation structure: PROC GENMOD, SASTM, V 8.2, 1999 ) • Classes:S0, S1, S2(setting the parameter value of the S0 group equal to zero). • Stratified Poisson regression: • TC =  +1*(Hygiene) +2* (temperature) + (0; Herd) + (0, ) •  = Intercept (population mean) • 1 = Partial slope (Hygiene package as class variable) • 2 = Partial slope (temperature as co-variable) • (0; Herd) = Random effect of herd 4. CONCLUSION The general hygiene affects the numbers of micro-organisms in the milk. The hygiene package produced a sustained improvement of milk quality coinciding with a reduction of milk contamination at the selling point. Despite the residual TC in water and containers, the milk at the farm and on intervention was of fairly good microbiological quality for further processing. The study suggests that in milk production area, besides udder infection and water quality, hygiene behaviour with respect to hand washing, container’s cleaning and disinfection are the key areas that remain of relevance to milk hygiene intervention. The promotion of the shelf life of the milk through credit incentives for accessing to material will certainly help to increase the stakeholders’ compliance.